2 1 8 PA THOGENIC DA CTERIA . 



The best method of obtaining a culture is to inoculate 

 a guinea-pig with tuberculous material, allow an artificial 

 tuberculosis to develop, kill the animal after a couple of 

 months, and make the cultures from the centre of one of 

 the tuberculous glands. 



Of course many technical difficulties must be over- 

 come. The tuberculous material used for inoculation 

 may be sputum, injected beneath the skin by a hypo- 

 dermic syringe. The animal is allowed to live for a 

 month or six weeks, then killed. The autopsy is per- 

 formed according to directions already given. A large 

 lymphatic gland with softened contents or a nodule in the 

 spleen being selected for the culture, an incision is made 

 into it with a sterile knife, or -a rigid sterile platinum 

 wire is introduced ; some of the contents are removed 

 and planted upon blood-serum. After receiving the in- 

 oculated material the tubes are closed, either by a rub- 

 ber cap placed over the cotton stopper, which is cut off 

 and pushed in, or by a rubber cork above the cotton, 

 the idea of this rubber corking being simply to prevent 

 evaporation. The tubes must be kept in an incubator 

 at the temperature of 37-38 C. 



Kitasato has published a method by which Koch has 

 been able to secure the tubercle bacillus in pure culture 

 from sputum. After carefully cleansing the mouth the 

 patient is allowed to expectorate into a sterile Petri dish. 

 By this method the contaminating bacteria from the 

 mouth and the receptacle are excluded, and the expecto- 

 rated material is made to contain only such bacteria as 

 were present in the lungs. The material is carefully 

 washed a great many times in renewed distilled sterile 

 water until all bacteria not enclosed in the mtico-purulent 

 material are removed ; it is then carefully opened with 

 sterile instruments, and the culture-medium glycerin 

 agar-agar or blood-serum is inoculated from the centre. 

 Kitasato has been able by this method to demonstrate 

 that many of the bacilli ordinarily present in tubercular 

 sputum are dead, although they continue to stain well. 



